The C/S architecture is a well-known client and server architecture, which is structure of software systems.
Generally, in the C/S architecture, a method for performing services in a server and a client is: once started, the server should wait at any time to respond to the service performing request sent from the client; the client is responsible for interface display and user interaction. When the user needs to send to the server an operation request to perform services, the client sends to the server a service performing request according to the user request, and waits to receive the performing process information or the performing result information sent from the server. The server is responsible for receiving and performing the service performing request sent from the client, performs the services according to the service performing request, and returns the service performing result to the client after the service performing completed.
Generally speaking, during the service performing, according to the received service performing request, the client can not intervene in the service performing process of the server any more. Which, in usual case, doesn't influence the use of the C/S architecture to satisfy service demands of the client, but there is an exception. In some software demands, it is possibly required that the user may intervene in the service performing of the server via the client. For example, the user may hope to decide the subsequent service performing action or performing flow of the server according to different situations occurred after the server performs the services to a certain stage.
But, at present, during the service performing of the server, the client may not control the server.